http://paleo.cortland.edu/tutorial/Timescale/Timescale3.GIF
Figure F7. Cenozoic events in climate, tectonics, and biota vs. d18O and d13C in benthic foraminiferal
calcite (after Zachos et al., 2001). VPDB = Vienna Peedee belemnite
http://odp.pangaea.de/publications/207_IR/chap_01/c1_f7.htm#60367
http://www.ruf.rice.edu/~leeman/GeoTimeSpiral.gif
“Outcrop” or cross section view
• Types of rocks based on geometry? (sedimentary, igneous, metamorphic)
• Order of events?
http://serc.carleton.edu/quantskills/methods/quantlit/DeepTime.html
Guiding principles geologist use when examining a rock outcrop
to determine order of events
principle of uniformitarianism:
physical processes acting today also acted in the past at comparable rates
-- the present is the key to the past;
principle of superposition:
younger sedimentary rocks overlie older rocks because a layer of sediment cannot
accumulate unless there is already a substrate on which it can collect
principle of original horizontality:
sedimentary rocks are deposited relatively horizontally because they settle out of fluid in
a gravitational field -- folds and tilted beds indicate deformation that postdates deposition;
principle of original continuity:
sedimentary rock units accumulate in continuous sheets, a layer exposed on one side of
a canyon likely spanned the canyon at one time;
http://serc.carleton.edu/quantskills/methods/quantlit/DeepTime.html
Guiding principles geologist use when examining a rock outcrop
to determine order of events
principle of cross-cutting relationships:
a feature that cuts across another is younger than that which it cuts;
principle of inclusions:
igneous and sedimentary rocks that contain inclusions of other rocks must be younger
than the rocks they include
principle of baked contacts:
an igneous intrusion "bakes" the rock surrounding it.
http://serc.carleton.edu/quantskills/methods/quantlit/DeepTime.html
In this image,
A is younger than C (superposition),
C is younger than I (inclusions, cross cutting),
I is younger than D, E and B (cross-cutting),
D (the fault) is younger than E and B (cross-cutting),
H, F, K and J have been tilted or folded (original horizontality),
G is younger than B, H, F, K and J (baked contacts).
In order from youngest to oldest, the sequence is as follows:
A, C, I, D (faulting), E, G, B, tilting, H, F, K. J.
http://serc.carleton.edu/quantskills/methods/quantlit/DeepTime.html